Physics - EMI/AC Question with Solution | TestHub

A ring of mass$4 \mathrm{kg}$is uniformly charged with a linear charge density$\mathrm{\lambda }=4\mathrm{ }\mathrm{C} {\mathrm{cm}}^{-1}$and kept on a rough horizontal surface with a friction coefficient of$\mathrm{\mu }=\frac{\mathrm{\pi }}{4}$. A time-varying magnetic field$\mathrm{B}={\mathrm{B}}_0{\mathrm{t}}^2$is applied in a circular region of radius$\mathrm{a}$$\left(\mathrm{a}<\mathrm{r}\right)$perpendicular to the plane of the ring as shown in the figure. Find out the time when the ring just starts to rotate on the surface. (take$\mathrm{a}=5 \mathrm{cm}$,$\mathrm{g}=10\mathrm{ }\mathrm{m} {\mathrm{s}}^{-2}$and${\mathrm{B}}_0=125$SI units)